Known lithography techniques to be used during procedures for manufacturing semiconductor elements include a double-patterning technique using ArF immersion exposure, EUV lithography, nanoimprint, and the like. As patterns have become smaller, those conventional lithography techniques entail various problems such as higher costs and lower throughputs.
Under such circumstances, applications of directed self-assembly (DSA) to the lithography techniques are expected. Directed self-assembly occurs through the spontaneous behavior of energy stabilization, and accordingly, can contribute to formation of patterns with high size precision. Particularly, by a technique utilizing microphase separation of a polymeric block copolymer, periodic structures that are of various shapes and of several to hundreds of nanometers can be formed through simple coating and annealing processes. Spheres, cylinders, lamellas, or the like can be formed depending on the composition ratio in the blocks of the polymeric block copolymer, and sizes can vary depending on the molecular weight. In this manner, dot patterns, hole patterns, pillar patterns, line patterns, or the like of various sizes can be formed.
The positions of phase separation patterns of a self-assembled material have fluctuations that cannot be artificially controlled. In a case where patterns of interconnects, contact holes, and the like are formed by using a self-assembled material, the fluctuations need to be restrained, and the accuracy of alignment between the upper-layer patterns and the lower-layer patterns needs to be increased.